When a device is connected to a computer, the computer needs to learn about the device to determine some characteristic features of the device. Some examples of the characteristic features of the device include the device type, data speed it can support, the vendor name, model number and release number. After learning about the device, the computer assigns a device driver before any computer applications can communicate with the device. This initial exchange of information between the computer and the device is called enumeration.
When a printer is connected to the computer, for example via a Universal Serial Bus (USB), the printer provides its model name and serial number to the computer. The computer checks whether a logical port has been created for the printer based on the provided model name and serial number. If no logical port has been created, the computer creates one accordingly. Subsequently, the computer loads and assigns a printer driver to the created logical port for the printer.
Fleet managed mobile printing is a usage model where a group of printers is centrally managed and shared among a group of users. This group of centrally managed printers usually includes mobile printers having the same model name but different serial numbers. In fleet managed mobile printing, a user connects his computer to any one of the centrally managed printers when he needs to print a document, and disconnects the printer from his computer after printing.
When a printer having a different serial number is connected to the computer, the computer creates a new logical port for the printer with a new instance of the printer driver pointing to it. Therefore in fleet managed mobile printing, if the user uses ten of the centrally managed printers (all having different serial numbers) for printing, there will be ten different logical ports being created in the user's computer even though all the printers are of the same model. These additional logical ports are unnecessary and take up computer resources.
If many ports are created in the computer, it is not easy for the user of the computer to determine the correct port to be used for the current printer. The user may run a software utility program to detect the port which is currently active as the port being used by the current printer. However, this still does not solve the problem of creating many unnecessary ports in the computer.
It is also possible to manufacture printers having both the same model name and serial number. In this case, only one logical port would be created for all the centrally managed printers since all the printers have the same model name and serial number. However, having the same serial number for all the printers will cause inventory tracking problems. It will also prevent some manufacturing and servicing tools from working properly.